Sainsbury's wouldn't turn away the business without good reason.

Many inner London schools are nothing more than zoos. Once the animals are out of the cage, the keepers lose control and aren't really responsible any more.

Sainsbury's can exclude who they like. They also need to retain the business of their decent customers, who may desert them if the shopping experience is interrupted by bad behaviour and is unpleasant.

In response to an earlier question, I think the kids from St.Dunstans are taken by a fleet of Chelsea tractors to Waitrose in Beckenham to do their shoplifting.